Elevator rope hitch



Jan. 10,1939. B. G. CARLSON ET AL 2,143,139

HYDRAULIC AUTOMATIC P TLOT Filed 001:. 23, 1936 4 Sheets-Sheet 1 INVENTORS Bari G. Carlsonfi mgadore W/(angoW WM K, HE! ATTORNEY Jan. 10, 1939. B. G. CARLSON ET AL 2,143,139

HYDRAULIC AUTOMATTC PILOT Filed Oct. 23, 1956 4 Sheets-Sheet 4 fig, 1U

"" mllll INVENTORS Beer? 6, Carbon 7726061018 N. If en yoW in M THEIR TTO RNEY Patented Jan. 10, 1939 UNH'E'ED STATES rarest orrica HYDRAULIC AUTOMATIC PILOT Application October 23, 1936, Serial No. 107,152

15 Claims.

This invention relates to automatic pilots for aircraft,- and, more particularly, to a barometric control for causing the craft to fly at a uniform altitude.

In prior devices, great trouble has been experienced in maintaining a uniform altitude, the airplane usually alternately ascending and descending above and below the altitude that should be maintained. In our invention we provide a simple device for maintaining uniform altitude without the hunting action of the prior. devices of this character.

A further improvement consists in means to control one 'or more of the control surfaces of the aircraft, at will, through the servo motor system normally controlled by the automatic pilot equipment so that the servo motor system may be made use of both when flying automatically and under control of theoperator. This is important in large aircraft where considerable manual efiort is required to move the control surfaces directly. I

A further improvement achieved by our invention is an improved form of hydraulic servo motor adapted for large movements of the rudder cables, for which the fixed pistons of the prior art are not adapted.

Further objects of the invention will become apparent from the following detailed description.

In the drawings,

Fig. 1 is-a side elevation, partly in section, of the automatic control unit, showing also diagrammatically the hydraulic servo motors and control surfaces actuated therefrom.

Fig. 2 is an enlarged sectional detail of one form of auxiliary control valve for theauxiliary servo motor.

Fig. 3 is a diagrammatic view of my improved barometric control means.

Fig. 4 is a transverse section of a modified form of auxiliary control valve.

Fig. 5 is a vertical section of our preferred form of hydraulic motor for operating the controls.

Fig. 6 is a sectional detail through the pick-off control box actuated by the barometric means.

Fig. 7 is a similar view showing the parts in the shut-off position.

Fig. 8 is a sectional view of the hydraulic servo motor on line 8-8 of Fig.5. A

Fig. 9 is a. partially exploded view of the pickoff control from the automatic pilot, showing the servo motor connected from the barometric control.

Fig. 10 is a face view of the clutch connecting the follow-up pulley with the automatic pilot mechanism. Our invention is shown as applied to an automatic pilot of the general type shown in prior Patent #1,992,970, dated March 5, 1935, to E. A. 5 Sperry, Jr., M. F. Bates, and Bert G. Carlson, one of the joint applicants herein. In such gyro pilots, a form of gyro pendulum or base line I is usually used as the base line for controlling the attitude of the plane fore and aft and laterally, 10 the gyroscope being mounted for oscillation about a transverse axis-2 within a gimbal ring 3 which, in turn, is mounted for oscillation about a fore and aft axis. The ailerons and elevators are controlled through some delicate controls about the 15.

two axes'of the gyroscope, such as air pick-off devices, and the follow-up connection from the elevator is brought back to the apparatus through the follow-up pulley 5'. It is the present practice to enclose the gyroscope and control parts in a 20 closed casing 41, from which air is continuously exhausted.

The air pick-off means for elevator control may comprise a semicircular cut-ofl' disc 1 (Fig. 9), secured to move with the gyroscope, and a pair 25 of ports 8 and 9 pivoted on the aircraft on an axis III in line with the transverse axis 2 of the gyroscope. The differential pressure drop in the pipes II and I2 leading to said ports is used to actuate the main servo motor 90 and elevator 9| 30 through suitable relay valve 92. Normally, the position of said ports about axis I0 is governed from the follow-up pulley 5 and alsoby whatever hand adjustment I3 is provided on the pilot. We prefer to also bring in the barometric con- 5 trol diflerentially through these same connections so that the changes of elevation are made through the gyroscope.

As shown in Fig. 9, the bracket H supporting the ports 8 and 9 is adjusted about the axis It! by 40 means of a link l5 from an arm l6 which is secured to the shaft ll of pinion l8, rotated from a second pinion l9. On the shaft of the latter is a short bevel gear sector 20. rotated from a bevel gear 2|, turned from planetary arm 22 45 of a differential 23. One side of said diiierential is shown as turned from the follow-up pulley 5, while the other side is shown as turned from a worm gear 24 driven from a worm 25 on the shaft of bevel pinion 26, the latter driven from 5 a bevel pinion 21 on a long shaft 28. Said shaft may be turned directly from the thumb piece l3 to cause the craft to climb or dive, but we also preferably connect the saidshaft to a small motor controlled from the barometric means. Said motor is shown as a small, light, reversible air turbine '29 driven in either direction from air nozzles 30 and 3!, connected to pipes 32 and 32' I leading to the barometric means 33 (see Figs. 1

' and its reduction gearing.

Said clutch also permits limiting the climbing or diving angle that may be introduced by the barometric means, so that in case of disarrangement of the turbine mechanism, the airplane will not be put into a dangerous attitude. Said limiting means may comprise a small stud 40 secured to the driven portion ll of the clutch 38,

1 which stud is attached by a chain 42 to a stud 43 secured to a collar 82 on a shaft 53' so as to limit the angular movement of the clutch part ll in either direction to the desired number of degrees. This results in limiting the movement of shaft 23 from the air turbine, since the added load stops the turbine, but leaves shaft 23 free to be turned from knob l3. It should be noted that the length of the gear 20 is also limited. This not only acts asa limit means, but prevents damage to the apparatus, since the pinion merely runs off the end of the short segment when turned too far and rotates no further, being held in this position by the leaf spring 44. The spring I5 is for the purpose of taking up lost motion in the gearing.

Preferably, the follow-up pulley 5 is detachably connected to the automatic pilot mechanism as through a friction clutch 53, one face of which is serrated as shown at 5| in Fig. 10, so that the pulley and shaft may be readily disconnected from the gyro pilot.

The barometric control proper preferably consists of a flexible container 52 of the type employed in aneroid barometers, but which in this case has a pipe connection 53 which may be opened or closed to the atmosphere at will. As

shown, said pipe connection connects with a port 54 in the control box 33, which may be either opened or closed to the atmosphere by the lateral movement of ,a slidable cover plate 55, the position of which may be controlled from a thumb piece 56. On the shaft of said thumb piece is shown 2. lug 51 engaging a fork 58 in the top plate.

As shown in Fig. 1,. the nozzles 30, 3| which operate the servo motor 29 are mounted within the casing 41, from which air is being continuously withdrawn. The box 33, however, is preferably enclosed in a separate casing 59 which is cut off-from the main casing and is open at the top to the atmosphere. The box 33 is shown as having two ports 51, 5| therein, connected respectively to pipes 32 and 32', and these ports are normally in line with the small slotted openings 62, 62' in the top plate 55 so that, in operation, air is drawn in through said ports and issues from the nozzles 33, 3!. As long as the pressure on both nozzles is equal, the turbine will stand still, but the differential pressure is controlled by a shutter 63 pivoted at 54, the movetion from the turbine 29 to the barometric means. This is preferably in the form of a cam 65 shown as mounted on shaft 28 turned from the turbine, against which bears a roller 56 on a lever 51 pivoted at 68. The lever 61 is connected by means of a spring 69 to the shutter 63 so that the tension of the spring, and thereby the loading of the flexible container 52, is varied as the turbine 29 revolves.- This means has been found to be very efiective in maintaining uniformly level flight, in that it causes the open port 82 or 62' to be closed somewhat prior to the time that the upper altitude is reached, thus causing the aircraft to level off. i

With the plate 55 positioned as shown in'Fig. 6, the barometric means is in operation, the port 55 being at that time closed so that the barometer is sealed. If it is desired to change the altihide or throw out the automatic means, the handle 46 is merely moved clockwise in Fig. 3, thus moving plate 55 to the right, shutting off the air supply to the nozzles 33, 3| and connecting the pipe 53 to the atmosphere. By this means the barometer can be designed to be sensitive to small changes of altitude, since its range may be made limited.

The automatic pilot in Fig. 1 is shown as operating one of the larger types of aircraft in which both a trim rudder or auxiliary control surface Ill and service rudder or'elevator 9| are employed. According to this system, a main servo motor 33 actuated directly from the relay 32 is employed for operating the service rudder 3|, while an auxiliary servo motor II is employed for operating the trim rudder l3 somewhat in accordance with the principles outlined in the prior patent of Bert G. Carlson, one of the joint applicants, #2,045,5'I9, dated June 30, 1936. According to this system, the auxiliary servo motor II is controlled by preponderating pressures in the main servo motor 90, but we have improved upon the prior system by increasing the sensitivity of the control of motor II. This may be ef- 13, H to the pipes 15, I6 which connect the relay 12 to the main servo motor 90. The differential pressure in said two pipes causes movement of the pistons 11 and 18 which are connected through the common'valve rod I! and which are normally centralized by opposed compression springs 8|, 8|. oil at pump pressure is supplied to said valve through a pipe 82', but a needle valve 33 is interposed in said pipe so that the flow therethrough is greatly restricted. Said pipe is shown as entering the valve block 84 through port 85. The entering oil passes downwardly, then laterally within the bore 36 housing the valve rod I9, so that when said rod is moved to the left, for instance, oil passes downwardly through port I31 and through the bypass valve 31 and into pipe 88 leading to one side of the cylinder ll. At the same time the other side of said cylinder is connected through the pipe 33 to the return side of the pump through port I33, channel 33 and pipe 34. It will be obvious that the reverse action takes place when the slidevalve 13 is moved in the opposite direction.

The operation of this relay valve is as follows. The airplane is normally flown through the operation of the main servo motor 90 and main control surface or elevator 9I. In case, however, there is continued pressure on one side of the control surface, so that a greater average pressure is maintained on one side of the piston in cylinder 90 than the other, the relay valve I9 will be displaced, causing oil to be admitted slowly into the cylinder II. This oil, although at pump pressure, is throttled down through the needle valve 83, so that the piston in cylinder II will not be moved unless the flow of oil is maintained for an appreciable time in one direction. In this event, the piston in cylinder II will be actuated to move the auxiliary control surface to change the trim of the craft and to relieve the tension on the main cables from the cylinder 90.

The relay shown in Fig. 4 operates similarly in principle, the parts being correspondingly marked, with primed numerals where different, although in this case the parts are arranged somewhat differently and the by-pass valve is not shown, being separated therefrom as shown in Fig. I. Preferably the crank handles I81 bypass valve 87' for the cylinder II and 95 for the cylinder 90 are cross connected so that one valve throws the other, and a common handle 96 may be provided for throwing both together. Said handle may be located adjacent the pilots seat and there may also be provided at that point auxiliary control handle 81 by which the pilot may operate the control surfaces with little manual effort through the same servo motors normally used in the automatic pilot. A simple method for effecting this result is by placing an electric switch 91', operated from the handle 91, in circuit with solenoids 98, 98' secured to the relay valve I2 (Fig. 4), When one or the other of said solenoids is excited, the valve rod is displaced and the piston in cylinder II operated.

Where long cable movement is required for movement of the control surfaces, the single cylinder and piston form of servo motor becomes cumbersome and undesirable. Figs. 5 and 8 illustrate a form of hydraulic servo motor designed for such use. According to this form of the invention, the hydraulic servo unit is in the form of a multi-cylinder rotary engine I00, the cylinder block IIlI being rotatably mounted in anti-friction bearings I02, I02 within the stationary housing I03. Said housing has a pair of annular ports I04, I04 and I05, I05 on each side of the interior thereof and the tops of the cylinder blocks each have a plurality of small ports I06, I06 bored therethrough on both sides. The dia metrically opposite pistons are placed 180? apart and the piston rods all engage the common stationary crank shaft I07. Oil under pressure is fed through one of pipes I08 or I08 into one of the port chambers I06, I06, while the other pipe returns the oil to the sump. It will readily' be apparent, therefore, that as each cylinder passes the intake port it will be forced outwardly under the oil pressure, and as it passes the outlet side the oil will be ejected therefrom. The engine is shown as coupled to a drive pulley I09 through universal coupling II 0, the usual control wires being connected to said pulley. With our improved construction, the abutting walls of the revolving cylinders and the housing adjacent the annular prots I04 and I05 are effectively lubricated by the oil under pressure passing into and out of the engine, whichpressure is maintained equal on both sides of the cylinder block.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described our invention, what We claim and desire to secure by Letters Patent is:

1. In an elevation control for aircraft automatic pilots, the combination with servo means for operating the elevator, of a barometric device, an auxiliary servo motor, a control device operated from said barometric device for controlling said auxiliary servo means, a controller for said first named servo means operated in part by said auxiliary servo means and follow-back means connecting said device and said auxiliary servo means for maintaining level flight.

-2. In an elevation control for aircraft automatic pilots, the combination with servo means for operating the elevator, 'of a spring loaded barometric device for controling said means, and means operated by movements of the elevator for varying the spring loading of said device.

3. In a control device for aircraft, the combination with an artificial horizon for controlling the elevator, of a flexible container closed to the atmosphere at will, a shutter connected to the movable side of said container so as to be moved as said container expands and contracts. an air port on each side of said shutter but out of contact therewith, a pair of oppositely acting air motors, one connected to each port, both motors being under the same negative pressure, whereby said motor is differentially driven in accordance with the coverage of said ports, controls at the horizon, the relative position of which is altered by said motors, and-a common means for rendering said motors inoperative and for opening said container to the atmosphere.

4. In an automatic pilot for aircraft, dual means for maintaining level flight comprising a gyro-vertical and an expansible, normally spring centralized container normally open to the atmosphere, means for closing the same at will, means brought into action by expansion or contraction of said container after closing, clue to ascent or descent of the craft, for altering the relation between the gyro-vertical and craft to maintain level flight, and follow-back means for altering the centralized position of said container with the operation of said last named means.

5. In a control device for aircraft, the combination with an artificial horizon for controlling the elevator, of a spring loaded flexible container of the aneroid barometer type, a shutter connected to the movable side of said container so as to be moved as said container expands and contracts, an air port on each side of said shutter but out of contact therewith, a pair of opposed air nozzles, one connected to each port,

means for subjecting both nozzles to the same negative pressure, means operated by said nozzles for altering the controls at the horizon from which the position of the elevator is controlled, and means operated by said last named means for varying the spring loading on said shutter for the purpose specified.

6. In an automatic pilot for aircraft, the combination with a service rudder and a hydraulic servo motor for operating the same, of an auxiliary rudder and an auxiliary hydraulic servo motor for operating said auxiliary rudder, including a relay valve connected to the supply a from said supply.

pipes to said first named motor so as to be moved by the preponderating pressure in said pipes, and adapted to supply oil at substantially pump pressure, but through a needle valve, to cause said second motor to slowly respond to continued preponderance of pressure in the supply pipes to the first motor.

7. In an automatic pilot for aircrafthaving a service and an auxiliary control surface, a source of fluid pressure, a fluid operated servo motor controlled from said pilot for actuating one of said surfaces, a second servo motor for actuating the other control surface, a relay valve connected across the supply lines to said first motor, and between said supply source and said second motor, and means for retarding the flow of fluid thereto 8. In an automatic pilot for aircraft having a service and an auxiliary control surface, a source of fluid pressure, a fluid operated servo motor controlled from said pilot for actuating one of said surfaces, a second servo motor for actuating the other control surface, a relay valve, for operating said second motor subject to prolonged unbalanced pressure on said first motor, and means operable at will for actuating said valve independently of the automatic pilot.

9. In a hydraulic motor for the control surfaces of aircraft and the like, a casing, a multicylinder engine rotatably mounted within said casing, each cylinder having a port transversely through the head thereof and adapted to register with substantially semicircular intake and outlet ports on the interior of said casing, and a common stationary eccentric crank shaft to which the pistons of said cylinders are connected.

10. In an auxiliary hydraulic pilot for aircraft, the combination with a service rudder and means for operating the same, of an auxiliary rudder and a hydraulic servo motor for operating said auxiliary rudder, including a hydraulic valve adapted to supply oil under pressure to said motor, said valve being responsive to unbalanced pressures on said service rudder.

11. A hydraulic servo motor system for aircraft, as claimed in claim 10, having an automatic pilot controlling the service rudder and electromagnetic means for operating said auxiliary motor independently of said automatic pilot.

12. In a hydraulic motor for'the control surfaces of aircraft and the like, a casing, a multicylinder engine rotatablymounted within said through the'head thereof and adapted to register with substantially semicircular intake and outlet ports on each sideof the interior of said casing, and a'common stationary eccentric crank shaft to which the pistons of said cylinders are connected.

13. In an elevationcontrol for aircraft automatic pilots, the combination with servo means for operating the elevator, of a barometric device, an auxiliary servo motor, a control device operated therefrom for controlling said auxiliary servo means, a controller for said first named servo means operated in part by said auxiliary servo means, and means associated with said device for causing said device to stop said auxiliary servo means prior to reaching the predetermined altitude, whereby hunting is prevented.

14. In an automatic pilot for aircraft, dual means for maintaining level flight comprising a gyro-vertical and an expansible, normally spring centralized container of the aneroid-barometer type, means brought into action by expansion or contraction of said container, due to ascent or descent of the craft, for altering the relation between the gyro-vertical and craft to maintain level flight, and follow-back means for altering the centralized position of said container with the operation of said last named means.

15. In a hydraulic servo motor system for aircraft having both service and trim control rudders, a hydraulic servo motor for operating the service rudder, an auxiliary hydraulic servo motor for operating the auxiliary rudder, and a relay valve connected to the supply pipes to said' first named motor so as to be moved by the preponderating pressure in said pipes, and adapted to supply oil at substantially pump pressure, but through a needle valve, to cause said second motor to slowly respond to continued preponderance of pressure in the supply pipes to the first motor.

BERT G. CARLSON.

THEODORE W. KEN'YON.

' casing, each cylinder having a port transversely 

